Underreamer



UNDERREAMER '2 Sheets-Sheet 1 Filed June` 12 1922 INVENTOR @mmf j?! um;

ATTORNEY Patented Nov. 13, i923.

.moi/ias JOHNSON iacconrfircn, or nnrnoim, niermann, assreiror., 'BY' Mnsivnns- SIGNMENTS, TO MCCORMICK DRILLING' A CORPORATION or MICHIGAN.

root detersivi', er nnrnoi'r, MICHIGAN,

UNDERREAIVIER.

Application filed June 12, 1822.

To all whom t may concern.'

Be it known that I, THOMAS J MCCOR- MrcK, a citizen of the United States, residing at Detroit, in the county of Wayne and State of Michigan, have invented new and useful Improvements in Underreamers, of which thefollowing is a speciiication.

This invention relates to improvements in` underreamers, the present invention being an improvement over that forming the subject matter of Letters Patent No. 1,401,545, dated Dec. 29, 1921.

An object of the invention is to provide a fixed pawl for holding the cutters in open position and means for insuring the closing of the cutters when they become filled with cuttings.

This invention also consists in certain other features of construction and in the combination and arrangement of the several parts, to be hereinafter fully described, illustrated in the accompanying drawings and specifically pointed out in the appended claims.

In describing my invention in detail, reference will be had to the accompanying drawings wherein like characters denote like or corresponding parts throughout the several views, and in which Figure 1 is a side elevation of the invention.

Figure 2 is a longitudinal sectional view.

Figure 3 is a sectional view taken at right angles to Figure 2.

Figures 4 and 5 are cross sectional views.

Figure 6 is a view of one of the rods 11 for supporting the pin 8.

Figure 7 is a view of the pin 8.

In these views 1 indicates the body of the underreamer which is provided with the central bore 2, the side bores 3 which terminate in the recesses 4 and the bifurcations 5. The jaws 6 have their Shanks 7 engaging the central bore 2, said aws passing through the bifurcations and said jaws are movably supported in the body by means of the pin 8 having its flattened ends engaging the flattened holes 9 in the heads 10 of the rods 11, said rods passing through the side bores 3 with the heads engaging the recesses 4. The upper ends of the rods are reduced, as shown at 12, and these reduced ends are received in Serial No. 567,767.

the sockets 13 formed in the upper enlarged part 14 of the body. This enlarged part is connected with the lower part by the reduced central part 15. A coil spring 16 is placed on each rod and has its upper end bearing against a nut 17 having screw threaded engagement with the rod and its lower end engaging the shoulder 18 which is formed at the junction of the lower part of the body with the reduced central part. The pin carries the rollers 19 which engage the cani portions 2O on the jaws so that the springs 16 will'hold the jaws in their upper and open position.

A pawl 21 is held in the upper part of the bore 2 by means of the set screw 22 and the inclined faces 23 of this pawl engage the inclined shoulders 24 at the upper ends of the shanks of the jaws and thus tend to hold the jaws in open position. The upper portions of the shanks are offset and the upper extremities are provided with outwardly eX- tending shoulders 25 which are adapted to engage recesses 26 formed in the walls of the bore at opposite sides thereof, said recesses being out of alignment with each other as shown.

y From the above it will be seen that the spring actuated rods, the pin and the rollers tend to hold the jaws in expanded position but said jaws are yieldingly supported and thus clogging of the jaws is prevented. The shoulders 25 arranged in the recesses 26 will insure the closing of the jaws in case they become filled with cuttings when the device is being pulled through thecasing.

It is thought from the foregoing description that the advantages and novel features of my invention will be readily apparent.

I desire it to be understood that I may make changes in the construction and in the combination and arrangement of the several parts, provided thatrsuch changes fall within the scope of the appended claims.

l/Vhat I claim is 1. An underreamer comprising a body, jaws carried thereby, means for yieldingly support-ing the jaws in the body, a stationary pawl in the body having inclined faces for engaging inclined parts on the jaws for normally holding the aws in open position, a projecting shoulder at the rear edge of the upper extremity of each jaw and the interior of the body having recesses for receiving said proj eet-ing shoulders.

2. An underreamer comprising 'a body, jaws carried thereby and yieldable means for supporting the jaws in lche body, such means comprising a, pair of rods slidably mounted in the body, spring means for normally holding the rods in raised position, :L pin having its ends carried by Jrhe rods, 10 rollers carried by the pin and engaging the jaws and guiding means for the upper ends of the rods.

In testimony whereof I affix my signature.

THOMAS JoHNsoN MCooRMieK. 

